(1) Field of the Invention
The present invention pertains to a collapsible bearing retainer that holds a bearing in place on a shaft of an electromagnetic device and its method of use. More specifically, the present invention pertains to a bearing retainer having compliant tabs that project axially from the retainer, where the tabs are deformed after assembling the retainer between a C-ring and several washers and a bearing on the shaft to ensure end play between the washers and the bearing.
(2) Description of the Related Art
An example of a prior art bearing retainer and its method of use are depicted in FIGS. 1-3. Bearing retainers of this type are often used on shafts of electromagnetic devices, such as electric motors. The prior art bearing retainer 10 of FIGS. 1-3 is also shown mounted on a shaft 12 of an electric motor. However, it should be understood that the bearing retainer 10 of the prior art is employed in other applications. It should also be understood that the bearing retainer of the invention yet to be described may be employed in applications other than the environment to be described.
Referring to FIG. 1, the internal windings (not shown) of the motor are to the left and the exterior of the motor is to the right. The shaft 12 is shown extending through a shaft opening 14 in an end bell or housing wall 16 of the motor. The dashed line 18 denotes the center axis of the shaft 12. The shaft 12 is provided with an annular groove 20 around its exterior surface. A C-ring 22 is mounted on the exterior of the shaft and engages in the annular groove 20, thereby providing an axially fixed stop on the shaft. The prior art bearing retainer 10 is next mounted on the shaft and moved into abutment against the C-ring 22 as shown in FIG. 1. A rubber washer 24, a phenolic washer 26 and a metal washer 28 are then mounted in succession on the shaft. The bearing 30 is next mounted on the shaft in its position shown in FIG. 1. The bearing 30 shown in the drawings is a spherical sintered powdered metal bearing however, other types of bearings may be mounted and retained on the shaft by employing the bearing retainer of the invention yet to be described.
In FIGS. 1-3, it is seen that the prior art bearing retainer 10 has a center hole 32 that is generally circular and is defined by a generally circular inner edge 34 of the retainer. The inner edge 34 of the retainer has an inner diameter that is only slightly larger than the exterior diameter of the shaft 12. This enables the bearing retainer 10 to slide easily over the exterior of the shaft to its position shown in FIG. 1. Also, the inner diameter of the bearing center hole 32 is slightly smaller than the exterior diameter of the C-ring 22 when the C-ring is mounted on the annular groove 20 of the shaft. This prevents the retainer from moving past the C-ring when an axial force directed to the left as viewed in FIG. 1 is exerted on the retainer. From the inner edge 34, the bearing retainer has a circular ring portion 36 that has axially opposite planar surfaces that extend radially outwardly to an annular flange 38 of the retainer. The annular flange 38 extends completely around the retainer and provides additional strength to the retainer. As can be seen in FIG. 1, the interior diameter of the annular flange 38 is determined so that the flange will engage over the exterior perimeter of the rubber washer 24. The annular flange 38 is turned outwardly at the exterior perimeter edge 40 of the bearing retainer. The prior art bearing retainer is also provided with a key projection 42 that is bent axially outwardly from the inner edge 34 of the retainer.
The motor shaft, with the bearing 30, the washers 24, 26, 28, the bearing retainer 10 and the C-ring 22 mounted thereon, is then assembled into the housing enclosure for the motor. Many motor housing enclosures have two end shields or end bells that are assembled together over opposite ends of the shaft. Although only one bearing assembly is shown in FIG. 1, there could be a like bearing assembly mounted on the opposite end of the shaft or some other type of bearing assembly supporting the opposite end of the shaft. For simplicity only one bearing assembly is described here. In assembling the two motor housing portions or the two end bells of the motor together, an axial force is exerted by the end bell 16 on the bearing 30. In one method of construction, the assembler pushes the two end bells together thereby creating the axial force exerted by the end bell 16 on the bearing 30. Depending on the particular motor construction and the assembling of the motor, the axial force could press the bearing 30, the washers 24, 26, 28, the bearing retainer 10 and C-ring 22 tightly together. Many prior art motor enclosures for smaller electric motors have their two end bells secured together by epoxy. The epoxy is later cured in an oven. As the epoxy cures, it shrinks to a certain extent, thereby further increasing the axial load or axial force on the bearing 30, the washers 24, 26, 28, the bearing retainer 10 and the C-ring 22.
The manual assembly of the motor and the shrinkage of the epoxy as it is oven cured could have a detrimental effect of creating an undesirable negative end play or no end play between the component parts of the bearing assembly. That is, the axial forces exerted by the motor end bell 16 on the bearing 30, the washers 24, 26, 28, the bearing retainer 10 and C-ring 22 cause these component parts to be pressed together with there being no end play or no axial spacing between adjacent parts. This situation can create friction between the metal washer 28 and the bearing 30 when the motor is operated. This friction, in turn, generates heat which can produce an undesirable burning smell when the motor is operated. This is particularly undesirable when the electric motor is used in a household appliance such as a dishwasher, clothes washer or clothes dryer.
What is needed to overcome the problem of friction heating of the prior art bearing is a way of retaining the bearing on the end of the shaft while ensuring a certain amount of end play between the bearing and the metal washer after the assembly of the electric motor is completed.